The present invention relates to a seatbelt apparatus mounted on a vehicle such as an automotive vehicle for constraining and protecting a passenger by a seatbelt and to a seatbelt apparatus provided with two pretensioners.
A seatbelt apparatus provided on a vehicle seat of the automotive vehicle or the like prevents the passenger from jumping out from the seat of the passenger by constraining the passenger with the seatbelt in case of emergency such as vehicle collision where a significant deceleration is applied to the vehicle, thereby protecting the passenger.
In the related art, as one of the seatbelt apparatus in the related art, for example, there is a three-point type seatbelt apparatus as shown in FIG. 9. In the drawing, reference numeral 1 designates a seatbelt apparatus provided on a vehicle seat 2, reference numeral 3 designates a seatbelt retractor fixed to a vehicle body near the vehicle seat 2 for constantly urging a seatbelt 4 so as to be withdrawably retracted, and locking the seatbelt 4 from being withdrawn in case of emergency, reference numeral 5 designates a tongue slidably supported by the seatbelt 4, reference numeral 6 designates a buckle located on the side of the vehicle seat 2 and fixed to the vehicle seat 2 or the vehicle body for being engaged by the tongue 5, and reference numeral 7 designates a belt guide mounted to an upper side of a vehicle side portion such as a center pillar 8 for guiding the seatbelt 4 withdrawn from the seatbelt retractor 3. A belt anchor portion 4a at a distal end of the seatbelt 4 withdrawn from the seatbelt retractor 3 is fixed to the vehicle seat 2 or the vehicle body.
With the seatbelt apparatus 1 configured as described above, when the passenger attaches the seatbelt 4, the passenger sits on the vehicle seat 2, withdraws the seatbelt 4 from the seatbelt retractor 3, engages the tongue 5 with the buckle 6, and then releases his/her hand from the tongue 5, whereby the part of the seatbelt 4 excessively withdrawn is retracted by the seatbelt retractor 3 and hence a slack of the seatbelt is removed, and the seatbelt 4 is attached to the passenger. In this case, the seatbelt 4 between the belt guide 7 and the tongue 5 functions as a shoulder belt 4b for constraining the shoulder and the chest of the passenger, and the seatbelt 4 between the belt anchor portion 4a fixed to the vehicle body and the tongue 5 functions as a lap belt 4c for constraining a lap (“lumber”) of the passenger.
Then, in case of emergency such as the vehicle collision of where a significantly large deceleration is applied to the vehicle, an emergency locking mechanism of the seatbelt retractor 3 is activated to lock the seatbelt 4 from being withdrawn and prevent the forward movement of the passenger by a force of inertia, whereby the passenger is constrained and protected. In particular, in the recent years, the pretensioner is provided in the seatbelt retractor 3, the belt anchor portion 4a, or the buckle or the like so that the pretensioner is activated in case of occurrence of emergency and pulls the seatbelt 4 to remove the slack of the seatbelt 4 quickly so that the forward movement of the passenger is kept as little as possible, whereby the effects of constraining and protecting the passenger are improved.
In the seatbelt apparatus provided with the pretensioner as described above, there is a seatbelt apparatus in which the pretensioners are provided in the seatbelt retractor and the belt anchor portion respectively, so that the pretensioner in the seatbelt retractor is activated first in case of emergency to retract the seatbelt by the seatbelt retractor, and then the pretensioner of the belt anchor portion is activated to pull the seatbelt and remove the slack of the seatbelt quickly for constraining the passenger (for example, see Japanese Unexamined Patent Application Publication No. 2001-287622).
In the seatbelt apparatus disclosed in Japanese Unexamined Patent Application Publication No: 2001-287622, since the two pretensioners are activated under two time frames, even when the slack of the seatbelt cannot be sufficiently removed by the first pretensioner, the slack of the seatbelt can be removed by the second pretensioner, whereby constraint of the passenger is ensured.
However, in the seatbelt apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2001-287622, when a first pretensioner 9 of the seatbelt retractor 3 is activated and the seatbelt 4 is retracted by the seatbelt retractor 3 as shown in FIG. 10(a), both of the shoulder belt 4b and the lap belt 4c are pulled toward the seatbelt retractor 3 as indicated by an arrow A.
Subsequently, a second pretensioner 10 of the belt anchor portion 4a is activated and hence the seatbelt 4 is pulled toward the belt anchor portion 4a as shown in FIG. 10(b), both of the lap belt 4c and the shoulder belt 4b are pulled toward the belt anchor portion 4a as indicated by an arrow B. Therefore, even though the lap belt 4c is pulled by the first pretensioner 9 and a slack of the lap belt 4c is removed, the shoulder belt 4b is pulled with the lap belt 4c in the opposite direction by the second pretensioner 10, and hence the lap belt 4c is loosened. Therefore, since the lap belt 4c which functions for constraining the passenger most is loosened, the effect of constraining the passenger cannot be sufficiently achieved.
Therefore, there remains a need to provide a seatbelt apparatus in which removal of the slack of the lap belt is ensured even though the two pretensioners are activated under two time frames, whereby the effects of constraining the passenger are satisfactorily achieved.